Present furnaces for cremation and like purposes are, with extremely few exceptions, based on old technology, hardly meeting the functional demands of today, especially concerning smoke emission. Apart from older constructions having electrical heating, in some instances supplemented with wood-firing, which are passed over here, cremation furnaces normally have a supporting source of heat in the form of an oil or gas burner which sees to that necessary combustion temperature is reached in the furnace chamber.
On incinerating biological material including cremation, as well as on incinerating other materials temporarily generating large smoke volumes, an efficient final burn-out of the fumes before any flue gas cleaning takes place is necessary. However, such efficient final burn-out is not achievable in existing constructions. On the contrary and as a result of the dimensioning of the combustion chamber and flue chamber for an average combustion value, heavy smoke emission through the funnel may occur on charging the furnace and on the disintegration of the burning material.
The supporting heating mentioned above is necessary as the material to be burned and especially the biological material has a low combustion supporting energy content.
One problem with incineration of the present kind is that the combustion has a very un-even progress with a high load during the initial phase and and a progressively subsiding load towards the end with corresponding gas generation.
The un-even progress of combustion and the associated un-even energy demand/consumption of present constructions result in varying temperatures of the fume or combustion gases, which in turn, have a tendency for forming streaks of streams resulting in un-allowable emissions of non burned out gases and of un-desired materials, e.g. toxic combines, mercury vapours and the like.
The main problem, technically seen, at cremation furnaces resulting in an un-even combustion load, is the batchwise charging of the furnace--cremations are executed one after the other--and this amplies that one can not, as in furnaces for continuous and even charging of material to be burned, keep up a continuous and essentially invariable progress of combustion.